German Pat. No. 33 12 133 describes a drive mechanism for an oscillating tool, e.g. for a saw blade used in a foam shaping and cutting machine.
The mechanism comprises a transmission device, e.g. a guided band under tension connected at its ends with both ends of the tool (the blade). The transmission device connected with the tool is oscillated by a connecting rod driven by a power-driven eccentric pin.
The foam shaping and cutting machine of this patent has its oscillating cutting band formed like a saw blade and used as the tool. The blade is held at both ends pivotably in a clamping device and is held by a band or rope guided under tension on a polygon-like course over rollers under tension.
This band simultaneously transmits the oscillating drive motion. This motion is caused by an eccentric pin mounted directly on one end of the shaft of an electric motor. The eccentric pin is engaged by the bearing of a connecting rod which is moved along a guide defining a slide which is connected with a driven band under tension.
Because of this slide transmission mechanism, lateral wandering of the band or rope extending centrally through the guide is strictly precluded.
However this system is very expensive and the drive mechanism is subject to a high degree of wear. The performance of this kind of drive mechanism is limited. Thus it can be used with an electric motor having a rotation speed of 1250 revolutions per minute and the displacement, adjustable by the eccentricity, may not exceed 20 mm.